ST CHARLES, Missouri (Reuters) - Missouri conservatives say they are rallying around U.S. Senate candidate Todd Akin despite his controversial comments about rape because they are outraged that "establishment" Republican Party leaders tried to railroad him out of the race.

A backlash has set in here in Akin's suburban St. Louis congressional district, where supporters said the national party had no right to attempt to force out a duly-elected candidate.

Backers described Akin as the "real deal," a politician fiercely committed to their social causes such as opposition to abortion, and to the Tea Party drive to downsize government.

Akin, 65, has defied widespread calls, including from Republican presidential candidate Mitt Romney, to step aside after he said women's bodies have natural defenses against pregnancy from "legitimate rape."

The uproar knocked Romney's campaign off message days before the Republican National Convention, and major party paymasters pulled millions of dollars in campaign advertising for Akin.

The gaffe has put at risk what was considered a likely Republican pickup of a Democratic-held seat in a state becoming more conservative. Republicans need a net gain of four seats in the November election to ensure they gain a Senate majority.

"At first I felt (Akin's comments) were offensive to women and insulting to my intelligence," said Lisa Payne-Naeger, a member of the conservative Missouri Grassroots Coalition, who has an online political radio show. "What changed it for me was the Republican establishment's effort to chop him off at the knees and install one of their own in the race."

Payne-Naeger said she was so angered by the "onslaught" from party leaders that she donated to Akin's campaign on Wednesday.

Nearly two dozen Missouri Republicans interviewed on Wednesday and Thursday, most of them in the St. Louis area but some in other parts of the state, expressed similar views.

Akin has seized on this theme, launching a "Help Todd Fight Back Against the Party Bosses" fundraising drive that his campaign said netted $100,000 in small donations this week.

On Friday he vowed to stay in the race until election day on November 6 -- and win.

"I may not be the favorite candidate of some people within the Republican establishment, but the voters made a decision and this is an election, it's not a selection," he said at a news conference.

Holding on to the Republican base of support is key to Akin's political survival, although he faces more major obstacles to defeating Democratic incumbent Claire McCaskill in November.

A poll by Republican group Rasmussen Reports released on Thursday gave McCaskill a 10-point lead over Akin, whose lead in other polls was as much as 11 points before the rape comments.

"Akin faces more of an uphill race now," said Jay Dow, a political scientist at the University of Missouri in Columbia. "The question is whether moderate Republicans will turn out."

'THE REAL DEAL'

Throughout his career as a state representative elected in 1988 and then as a congressman, Akin has been a staunch Christian and social conservative who has fought abortion and promoted the right to gun ownership.

"Todd Akin is firmly grounded in his Christian beliefs," said Kenneth Williams, Republican committee chairman for Sainte Genevieve County, who said he gave $100 to Akin's campaign on Wednesday. "He's the real deal."

The congressman's stand on fiscal issues and willingness to buck the party line -- he voted against the unpopular 2008 bank bailout and against President George W. Bush's education reform known as No Child Left Behind -- has also endeared him to the anti-establishment Tea Party movement.

"Akin has real Tea Party credentials," said Bill Hennessy, founder of the St. Louis Tea Party, who lives in Akin's district and has voted for him since 2000.

Hennessy recalled Akin was the only politician who showed up at the group's April 15, 2009, "Tax Day" rally in downtown St. Louis and adhered to an order not to do any politicking.

Akin's ability to straddle America's two main brands of conservatism -- fiscal and social -- enabled him to garner enough support from Christian conservatives and Tea Party adherents in the August 7 Republican Senate primary to win by 6 points.

Anyone who thinks the congressman may yet exit the race does not know Akin, said John Putnam, Missouri state coordinator for the national Tea Party Patriots group and chairman of the Jasper County Republican Party, who has known Akin since 1984.

Patsy Liszewski, who described herself as "just a grandma" and member of the St. Louis Tea Party Coalition, said she would prefer Akin get out of the race.

"But if he stays in, I will vote for him and campaign for him because our main goal is to beat Claire McCaskill," she said.

"I support him probably even more than I did before," said Molly Nesham, a home-schooling mother who also teaches at a Christian school and likes Akin's stand on abortion. "He made a mistake and the Republican Party abandoned him."